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Axial flow pumps often experience uneven distribution of axial force on the blades when deviating from design conditions, which can easily lead to local damage to the pump blades. In response to this issue, this article conducts a detailed study on the hydraulic and axial force characteristics of large vertical axial flow pumping stations in China based on constant and non-constant numerical simulation research methods. Research has found that under biased operating conditions, due to the angle between the water flow direction inside the impeller and the impeller blades, the water body collides with the blades, resulting in concentrated pressure distribution on both sides of the inlet side of the impeller blades. Under low flow conditions, the high axial force area of the impeller blade is concentrated in the middle and rear position of the suction surface, while under high flow conditions, the high axial force area is widely distributed. Under the conditions of 0.8 Q to 1.4 Q , the fluctuation of axial force on the impeller blades is mainly affected by the rotation of the impeller blades. However, under low flow conditions, due to the turbulence of the flow state, there is no obvious pattern of axial force variation on the impeller blades. In addition, under different flow conditions, there is no obvious pattern in the fluctuation of axial force on the guide vanes. This also proves that there are problems such as uneven axial force distribution and no periodic changes in the impeller blades under low flow conditions, which can easily lead to damage to the impeller blades. The above analysis can provide some reference for the design of impeller blades.

In the process of slope protection, it takes some time for the root system of plants to grow. Before the plant root system forms a developed root system, its reinforcement function cannot be exerted, and the stability of the slope cannot be effectively guaranteed. Aiming at the deficiency of plant slope protection technology, a new structural form of combined support of living stumps and bamboo anchors is put forward in this paper. Two groups of slope model tests with or without bamboo anchor and timber frame beam support are established. Through experiments, the variation law of axial force and bending of bamboo anchor under the condition of bamboo anchor and timber frame beam support is summarized, and the influence of the bamboo anchor and timber frame beam support on slope displacement and slope deformation is compared and analyzed. The relevant conclusions are summarized as follows: (1) The bamboo anchor in the slope is a kind of \"tension–compression–bending composite member\" with tension as the main function. Under the load on the top of the slope, the axial force and bending moment of the anchor on the top of the slope are significantly greater than that of anchors in the middle and toe of the slope. (2) Compared with the slope without bamboo anchor and timber frame beam support, the displacement of the slope with bamboo anchor and timber frame beam support is smaller, which has obvious supporting effect on the middle of slope. (3) The settlement depth on the top of the slope with bamboo anchor and timber frame beam support is less than that of the slope without bamboo anchor and timber frame beam support, and the slope has no obvious sliding phenomenon. Bamboo anchor and timber frame beam structure can also restrain the deformation of the slope to a certain extent.

Due to the localized high stress transmission and plastic deformation uncertainties, certain threads at the root of fasteners may experience extremely high stress in threaded connections, potentially leading to structural strength failure and premature fatigue. This study proposes an analysis method for stress distribution considering plastic deformation based on an analytical model of thread axial force distribution within the elastic range. A refined finite element model considering the helix angle of threads was established, and a stress distribution analysis of thread teeth was completed. The accuracy of the finite element model was verified through comparison with theoretical calculations. Additionally, to study the influence of different factors on the axial stress distribution of threads, a finite element model of standard threaded connections was established, in which parameters such as preload level, number of engaged threads, and root radius were taken into account.

A numerical analysis is improved to study the effect of vibration on temperature history, heat generation, and mechanical properties during the friction stir welding process with different welding speeds. In this investigation, smoothed particle hydrodynamics (SPH) was applied to improve the 3D numerical analysis for simulation of the friction stir welding (FSW) process and friction stir vibration welding (FSVW) under different welding speeds. According to the experimental analysis, the grain size of the FSVW-ed sample is finer compared with that of the FSW-ed sample. The analysis was validated through a comparison of the simulated thermal cycles with the experimental results. There was a close agreement between FEM and experimental values. The results indicated that the vibration increased the mechanical properties such as von Misses stress and also thermal properties of the FSW-ed sample. The vibration in the FSW process can lead to an enhanced plastic material flow and also improve the weld quality by enhancing the plastic material flow near the tool. The shear zone volume (SZV) develops from 289.56 mm 3 for the FSW process to 367.34 mm 3 for the FSVW process. It was found that the axial forces, traverse force, and tool torque with respect to different steps (plunging, preheating, or dwelling time and traveling) in FSVW is lower than those in the FSW.

Assessing failure pressure is critical in determining pipeline integrity. Current research primarily concerns the buckling performance of pressurized pipelines subjected to a bending load or axial compression force, with some also looking at the failure pressure of corroded pipelines. However, there is currently a lack of limit state models for pressurized pipelines with bending moments and axial forces. In this study, based on the unified yield criterion, we propose a limit state equation for steel pipes under various loads. The most common operating loads on buried pipelines are bending moment, internal pressure, and axial force. The proposed limit state equation for intact pipelines is based on a three-dimensional pipeline stress model with complex load coupling. Using failure data, we investigate the applicability of various yield criteria in assessing the failure pressure of pipelines with complex loads. We show that the evaluation model can be effectively used as a theoretical solution for assessing the failure pressure in such circumstances and for selecting appropriate yield criteria based on load condition differences. Assessing failure pressure is critical in determining pipeline integrity. In this study, based on the unified yield criterion, authors propose a limit state equation for steel pipes under various loads which can be converted into a series of failure pressure evaluation models for pipeline with different yield criteria.

This paper studies mainly error sources of current external force sensing algorithms and presents external force sensing algorithms of continuum robots using superelastic NiTi backbones. Axial compression is deliberately taken into consideration in analytical dynamics for facilitating the later analysis of error sources. The analytical dynamics of multibackbone continuum robots is established by Lagrange equation in a simple and concise manner. Experiments show that the stress–strain relationship is significantly different with or without external force, and we provide some insights into the feasibility and limitations of dynamic model. Then, an extend intrinsic force sensing algorithm (EIFS) and an external force observer based on generalized momentum method (EFOGM) are developed. Both of them only depend on joint-level information. The effectiveness of both force sensing algorithms is validated by simulations and experiments. Mean absolute error of EIFS using real-time axial strain is 0.0980 N, while mean absolute error of EFOGM using real-time axial strain is 0.0977 N, respectively. Experiments show that the main sources of force sensing algorithm error are: (1) the estimated external force compensates the force part caused by axial compression and (2) model error from nonlinear stress–strain relationship of cable tension-induced deformation and external force-induced deformation under the loading and unloading force stage.

This study investigated the impact of axial load on the dynamic response of reinforced concrete (RC) members to asymmetrical lateral impact loads. A series of asymmetrical-span impact tests were conducted on circular and square RC members with and without Carbon Fiber Reinforced Polymers (CFRP) while varying the axial compression ratios. The impact process was simulated using ABAQUS software, and the time history curves of deflection and impact were measured. The study found that specific impact loads caused bending and shearing failures. The axial compression ratio ranged from 0.05 to 0.13 when the impact curve reached its maximum deflection before the component’s impact resistance decreased. Analysis of the impact point and inclined crack location revealed that axial load affects the maximum local concrete. The speed of inclined crack penetration and inclined cracks take longer to form, with weaker resistance to damage to local concrete when the axial compression ratio is between 0.05 and 0.13. When the axial compression ratio is greater than 0.13, inclined cracks form sooner with more brittle and severe damage to the impact point’s concrete. The study also identified key parameters affecting the dynamic response of RC members, including impact height, CFRP layer thickness, axial force, and impact location. Thicker CFRP layers in RC can improve impact resistance, especially when the impact location is farther from the center. However, there is a limit to the impact of axial force on this resistance.

This paper discusses the use of two buoyancy schools in determining the axial forces in the drill string, which leads to the duality of the solution. The difference in the results in determining the true and effective force and their relationship with each other using the strength of stability were revealed. It is shown that only the true force can be used to calculate the stresses and deformations of the drill string elements, since their actual values correspond to this force. At the same time, taking into account the effective forces, it is possible to more fully use the actual stability of the drill string, increasing the permissible loads on the bit and increasing the penetration rate. Thus, the presence of two buoyancy schools and, accordingly, two types of axial forces, makes it possible to more accurately and comprehensively assess the operability of the drill string.

To study the axial compression performance of aluminum foam-filled steel tube and empty steel tube as objects, such tubes are studied in this paper, which explores the carrying capacity and deformation behavior of aluminum foam-filled steel tube with different lengths under a quasi-static axial load through experimental research. The carrying capacity, deformation behavior, stress distribution, and energy absorption characteristics of empty steel tubes and foam-filled steel tubes are compared through finite element numerical simulation. The results indicate that, compared with the empty steel tube, the aluminum foam-filled steel tube still presents a large residual carrying capacity after the axial force exceeds the ultimate load, and the whole compression process reflects steady-state compression. In addition, the axial and lateral deformation amplitudes of the foam-filled steel tube decrease significantly during the whole compression process. After filling the foam metal, the large stress area decreases and the energy absorption capacity improves.

Aiming at the problem pertaining to small area at the end of the tube and the asynchronous rate of traditional mechanical forming and electromagnetic forming processes, a new technology of axial compression electromagnetic bulging was proposed, which was performed on a 5052 aluminum alloy tube. In this study, multiple sets of electromagnetic coils were arranged. At the moment of discharge, the radial electromagnetic force generated by the bulging coil bulges the tube, and further, the booster coil generates axial magnetic force at the end of the tube, which leads to axial feeding of the material in time. Based on multi-physical field element simulation and experimental study, the influence of main process parameters on uniform tube bulging was analyzed, and it was revealed that the axial magnetic force produced by the booster coil at the end of the tube is the main factor that improves the plastic deformation ability of the tube in the process of axial compression electromagnetic bulging. The principal stress of a typical point changes from biaxial tensile stress state to one tension one compression state, and the proportion of compressive stress increases, leading to the increase in the forming limit.